"It's fun, it's addicting. Everyday you come in here and get to push yourself to a new level," said one athlete. "You never know what you're going to do but you know you're going to get a full body work out with it."

It's an exploding fitness phenomenon.

There are more than 50 gyms in northeast Ohio dedicated to the cross fit strength and conditioning program.

"You have some people who come in and they just want to lose weight. They'll lose a great deal of weight, but more importantly, their body will change," said trainer Carl Sandridge.

Trainers claim that the same routines can be used for both the elderly and cage fighters preparing for a bout. Carl Sandridge of Ctown Cross Fit adds it's all about scalability.

"The movements don't have to differ, it's just the intensity level," added Carl Sanridge.

But with such intensity can come danger -- things like slipped discs, muscle tears, or something called rhabdomyolosis which, if left untreated, could be life threatening.

"The muscle fibers break down and they release a protein into the blood stream called myoglobin. That is not meant to be in the bloodstream. So then what happens is the kidneys try to pick it up. The ultimate side effect if it gets to that point is that it can cause kidney failure because it plugs up the kidney," said Physical Therapist Angela Page.

Physical therapists say cross fitters have to watch out for three symptoms, muscle pain, extreme muscle weakness and dark urine, due to overloaded kidneys, and participants doing too much too fast.

Mr. Sandridge says they prevent injury through careful instruction and good communication.

"You get better, you get stronger you get in better shape but more than anything it's a wellness program. it's not about who's the biggest, who's the fastest. It's a goal for optimal health," added Mr. Sandridge. "You become very conscious about what you're eating you want to have that brownie or that cookie. But you're like it's that much more weight or sugar I'm going to retain when we have to do pull ups."

Sandridge credits social media for helping foster the strong sense of community and culture that fuels the athletes.

"The friendship aspect of it is really important because that's what keeps you coming back," Mr. Sandridge said.